Last



March 22,1927.

W. A KRENTLER 2 Sheets-Sheet 1 ll ILr March 22 1927.

heats-Sheet 2- Patented Mar. 22, 1927.

UNITED STATES PATENT OFFICE.

WALTER A. KRENTLER, OF DETROIT, MICHIGAN, ASSIGNOR T0 KRENTLEB-ARNOLD HINGE LAST COMPANY, 013 DETROIT, MICHIGAN, .A CORPORATION OF MICHIGAN.

LAST.

A'p'plication filed December 8, 1925. Serial No. 74,166.

My present invention is a novel and improved construction of two part last, and improved hinge connections therefor.

In the construction of wooden lasts for use in the manufacture of boots, and shoes, particularly where two part lasts are employed, having relative movement between the forepart and the heel part to produce shorten ing and lengthening of the last, it is of the utmost importance to provide a hinge construction which will keep the last parts tightly united. The strains upon a wooden last and particularly upon the hinge members of a two part last, constantly tend to loosen the connecting members and the torsional twist during levelling, sole laying, heel nailing, and similar operations involving heavy strain upon the last, must be not only overcome by relatively rigid and strong hinge connections, but it is important to have means to compensate for, and automatically return the last parts to, correct position, when sprung slightly in such work. Heretofore efforts have been made to provide coiled springs, flat curved springs, horseshoe springs, and the like, to keep the two parts tightly engaged, but such .prior devices have not been entirely satisfactory in use and wear. In my copending application Ser. No. 745,364, I have illustrated, described and claimed broadly my novel type of accordion spring, or connecting spring plate member having laterally extended convolutions to provide desired tension, great strength and high degree of resiliency. This provides a substantially constant and practically the same tension on the last parts at all times,'whereas the former springs had a continual yielding tension, increasing as the parts were moved, while decreasing as 'the parts wore loose. In my accordion spring the tension holding the last parts together is substantially constant at all times, and thus a uniform degree of resiliency can be accurately secured and constantly main tained, providing a better working last as it is collapsed and lengthened, and a more uni formly wearing last construction, insuring long life and efficiency.

In my present invention I have improved the accordion type of spring claimed broadly in my said prior and copending case, and have devised an addition-which I have designated as a dutchman to enable the accordion spring member to securely and snugly fit the recesses in the last parts and to thus cooperate with the laterally extending convolute portion or portions of the accordion spring, to snugly and accurately fill the recesses in the last parts, particularly across the line of cut dividing the forepart and heel part, and thus to prevent distortion sidewise of the two last parts. Various modifications of this form are herein illustrated and claimed. p

A further feature consists in the provision of a simple additional means to also prevent lateral distortion of the last parts, such as the driving in of a metallic member into one face of the last which will form and co operate with a groove in the opposite face of the last and thus still further prevent lateral displacement.

While I may utilize my present improved type of accordion spring as the sole connecting member, and'either with or without any central pivotal connection between the forepart and heel part, I may also utilize the same, together with an additional link mem-v ber, as will be more fully described and claimed.

Referring to the drawings, illustrating preferred embodiments of my invention,

Fig. 1 is a side view,'partly in cross-see tion of my improved accordion spring as the sole connecting means between forepart and heel part of the last;

Fig. 2 is a cross-sectional fragmentary View showing the last parts in collapsed or shortened position;

Fig. 3 is a fragmentary tion;

Fig. 4 is a plan view of the spring and dutchman united;

longitudinal sec- Figs. 5 and 6 are side and end views respectively of the dutchman shown as a separable member;

Fig. 7 illustrates a modification of my accordion spring and dutchman; and

Fig. 8 illustrates a still further modification in side view;

Fig. 9 is a side view, partly in cross-sec tion, of my present spring in combination with a reinforcing link and pivotal pin;

Fig. 10 is a view, partly in cross-section, showing the spring and link connection with the last parts in collapsed position;

Fig. 11 is a fragmentary longitudinal sectional view of the same construction; and

Figs. 12 and 13 show in side view the accordion spring and the cooperating link member respectively.

Referring to the drawings, I have illustrated a typical form of wooden last having a forepart 1, and heel part 2, divided on a well-known type of line of cut, presenting the faces 3 and 4, the curved surface 5 and the abutting shoulders 6 and 7. In the opposite abutting faces of the forepart land heel part 2, are formed or cut recesses 8 and 9 respectively, to receive the connecting member 10. Transverse bores 11 and 12 in the forepart and heel part respectively are also provided to receive the rivets or pins 13 and 14, which go through corresponding recesses 15 and 16 in the connecting member 10.

My uniting link and member 10 is preferably formed with a laterally convolute or sidewise extending spring portion 20, which, with the offset portions adjacent the pin receiving recesses 15 and 16, are preferably of a width sufiicient to accurately fill the width of the recesses 8 and 9, and hence bear against the opposite walls of said recesses. Also I prefer to position and proportion the ends of the member 10 with the convolute portion 20, so that the latter will extend across the line of cut 5 and hence afford a bearing upon a portion both of the forepart 1 and heel part 2 adjacent said line of cut. Fitted to the accordion spring member 10 and also extending across the line of cut 5, is the dutchman 21, thus giving a further bearingacross the line of cut 5 and both the forepart and the heel part. This dutchman may be formed in any suitable and desired manner. As shown in the last, Figs. 1 and 2 and 3, and as illustrated in detail, Figs. 4, 5 and 6, the dutchman 21 is a U- shaped member adapted to have downwardly extending prongs 22, 22, at either end, to [it within any appropriate, suitable and corresponding recesses in the portion 20 of the spring member 10. The entire bearing tension is inwardly and hence the part 21 need not be welded or otherwise permanently secured to the spring 20. It may, however, be desired to form this part 21 as shown in Figs. 7 or 8; wherein the dutchman there designated as 24 in Fig. 7 is welded or otherwise permanently secured to the part 20 of the spring 10 and in Fig. 8 as shown at 25 an integral portion of the spring 10 being stamped directly out of the part 20.

In either of the forms as above explained, the connecting spring 10 has a bearing across the line of cut 5 and interlocks the forepart and heel part thus firmly against lateral distortion. In the operation of the last parts, when they are sprung from lengthened to collapsed position and vice versa, the spring member 10 yields sufiiciently to allow the last parts to snap by the center or axis on which the parts turn as the faces move around the curved line of cut 5, the pins 13 and 14 being respectively below this axis or center when in lengthened positionFig. 1and above the axis when in collapsed position, Fig. 2.

In the modification illustrated in Figs. 9,

10 and 11, I have shown my improved accordion spring member in combination with a central pivot pin 31 and an additional rigid link 33. In this form the spring member 30 while provided with the dutchman 21 must also be provided with a central slot 35 preferably in the form of a cam to give an arcuate path for the central pivot pin 31, the spring 30 and its convolutions beyond the path 35 and pin 14, yielding sufliciently as the heel part and forepart snap above or below the axis of turning, which in this form is the pin 31. The link 33 has the opening 37 to fit over the forward pin or rivet 13, while the other end of the link 33 has the opening 38 to fit snugly on the pin 31, thus giving the combined effect of a rigid and yielding link construction.

As explained more fully in my said copending application, I prefer to form one of the pins, preferably the heel pin 14, with a substantially long conical face 40, which when driven in will pick up under spring tension the overlapping bearing surface 41 at the adjacent end portion of the spring 10, or 30, thus putting the entire structune under spring tension at the start as the parts are united. I have claimed this feature in the process of assembling the last parts thereby more fully in said copending case, but I prefer to utilize this advantageous feature in the present form also.

In Fig. 3 I have illustrated a further simple and very efficient means to prevent lateral displacement of the last parts during operation, particularly when a single link member, such as the spring 10 is employed to connect the two parts, and without a central pivot pin. This means consists in driving into one of the faces, preferably on the round portion 5 of the line of cut, a tack or other member 50, allowing the head 51 to protrude and become imbedded in the adjacent face of the other part 1. Then as the last is orked back and forth a few times the head 51 will automatically form a groove 52, and thus elfectively providing an interlocking head and groove connection between the two parts and prevent their being displaced laterally through torsional strains. A plurality of such tacks and grooves can be utilized if desired.

My invention is further described and defined in the form of a claim as follows:

A last having a forepart and a heel part relatlvely movable, a connecting spring member and means associated with said spring member to span the joint between the 15 fore part and heel part and bear upon the adjacent surfaces of said fore part and heel part.

In testimony whereof, I have signed my name to this specification.

WALTER A. KRENTLER. 

